This invention relates generally to integrated optics and, more particularly, to addressing arrangements for optical modulators and to methods of addressing optical waveguides for modulation.
Integrated optics has assumed a major role in information handling, communications and data processing systems. It is attractive because of the wide inherent bandwidth of optical devices and because of the many specialized features of optical waveguides.
Optical data links can be made to be smaller, cheaper and more reliable than their conventional counterparts. They are less susceptible to information degradation from electromagnetic interference, vibration, temperature changes and crosstalk. Where secrecy in communications is important, integrated optics offer the important advantages of electrical isolation and increased communications security.
In some integrated optics applications it is sometimes necessary or desirable to use a plurality of optical waveguides. A typical example of such a use is in the line-by-line addressing of a display device by an array of parallel optical waveguides.
In such applications it is usually necessary to modulate the light propagating through selected ones of the plurality of optical waveguides. A simple and effective method and apparatus for selectively addressing and modulating selected members of a plurality of optical waveguides are desirable.
Methods and devices for modulating light propagating through optical waveguides are known. Examples of such methods and devices are found in copending commonly assigned applications Ser. No. 621,312, filed Oct. 10, 1975, and 710,484, filed Aug. 2, 1976 now U.S. Pat. No. 4,050,027.
These applications disclose the modulation of light propagating through an elastomeric waveguide by changing the cross-sectional shape of the elastomer.
It has long been known to modulate light propagating through a liquid crystal waveguide by creating a field across the waveguide. This sort of waveguide modulation is disclosed, for example, in U.S. Pat. No. 3,838,908. That patent and copending, commonly assigned United States application Serial No. 542,786, filed Jan. 21, 1975, now U.S. Pat. No. 3,989,355, show examples of the complex matrix addressing systems normally used to modulate light propagating through liquid crystal materials.
Modulation of individual ones of a parallel array of waveguides by means of an electrical field is shown in U.S. Pat. No. 3,841,733. A common electrode is placed on one side of the waveguides and a separate individual electrode is placed on the opposite side of each waveguide. However, separate electrical connections must be made to each of the individual electrodes. The individual electrodes are separately and individually addressed. A less complex addressing means is desirable.